Balance computer



BALANCE COMPUTER Filed Feb. 25, 1941 4 Sheets-Sheet l TOTL \X/EIHT POUNDS l CENTS]? 55 ADJU5TMENT5\\\ WEIGHT BALANCE v GALLONS TOTAL CARGO FUELTANK5 PA55ENGER5 INVENTOR [aw/'5 W /m/77 ATTORNEYS Apia-5E W BALANCE COMPUTER Filed Fabe, 25, 1941 4 Sheets-Sheet 2 INVENTOR [aw/5 W 077m BY M ATTORNEYS April 10,1945. L. w. M 2,373,566

BALANCE COMPUTER Filed Feb. 25, 1941 4 Sheets-Sheet 3 F1K: E

INVENTOR [aw/'5 M //77/77 April 10, 1945, L, w W 2,373,566

BALANCE COMPUTER i gash INVENTOR Lew/s 14 /mm BY 1 and. 1/11/1111,,

ATTORNE 5 commercially as Patented Apr. 10, 1945 BALANCE comma Lewis W. 1mm, Glendale, CallL, assignor to Librascope, Incorporated, Burbank, C

ration of Calliornia aliL, a corpo- Application February 25, 1941, Serial No. 380,487

8 Claims.

The present invention relates to computing mechanisms and has as its principal object the improvement of balance computers of the general character disclosed in my prior patent number 2,179,822 issued November 14, 1939, although certain of the mechanisms included in the instrument herein disclosed are useful in computers adapted for other uses.

Prior to the commercial introduction of instruments embodying the invention disclosed in my prior patent, above identified, which are known Librascope" balance computers, the loading of transport planes, bombers, and similar aircraft required extended longhand computations for determining'gross weight and the fore and aft position of the load center for each particular distribution of the weights making up the load. The invention disclosed in said prior patent, however, provide a computer for automatically indicating variations in the location of the load center with cargo stowed and passengers and crew stationed in various locations with respect to the normal load center of the craft.

The specific objects of the present invention include reduction or the number of settable devices which the operator is required to adjust in computing the load center location for a given weight distribution, provision for indication of the effect upon load center location of the shifting of weights already entered, without requiring alteration of the weight settings, and mechanicalimprovement and-simplification of.the computing mechanism controlling the indicating devices.

The foregoing, together with other objects of the invention, preferably are accomplished by the provision of a control board carrying a single settable device for each of a plurality of classes of loads, e. g., passengers and cargo, regardless of their distribution within the spaces provided therefor, and the provision in combination therewith of associated settable devices for indicating changes in the respective positions of each of said classes of loads without altering the settings of the former devices. Additional settable devices are provided for other classes of loads, e..g., fuel I along the line 6-5 of Figure 5' and oil, and any or all of these latter devices may beutilized to indicate the-total weight of a load of a given class even though it is distributed in a plurality of tanks in different locations with respect to the normal load center 01' the craft, provided only thatsuch tanks are to be filled and emptied in a predetermined order. This reduction in the number of settable devices makes possible the simplification of the computing mechaplan as hereinafter described in detail.

The novel features of the invention are set forth with particularity in the appended claims. The invention itself, however, together with additional objects and advantages thereof will be best understood from the following description of a specific embodiment, when the same is read in connection with the accompanying drawings, in which:

Figure 1 is-a front view of the control panel of an instrument embodying the present invention;

Figure 2 and 3 are rear Views of the panel of Figure 1 illustrating the. computing mechanism mounted thereon; 1

Figure 4 is a plan view of the panel illustrating portions of both the controls and the computing mechanism;

Figure 5 is a detail computing mechanism;

Figure 6 is a detail view, partly in section, taken view of a portion of the Figure 7 is a detail view of sociated with the passenger load setting mecha nism;

Figure 8 is an elevational view, partly in cross several manually operable devices for setting the the mean wing chord of an airplane.

A single rotatably mounted knob I2 is provided on the panel In for entering the number of passengers to be carried, a predetermined average weight for each passenger usually being assumed, and said knob has an indicating portion I3 movable with respect to a weight scale II and a passenger number scale l5 so that the weight and number of passengers will be approximately indicated upon rotation position.

AdJacent thereto on the panel Hi there is rotatably mounted a passenger weight distribution of the knob to a selected knob l1 having an indicating portion l8 mov-v.

the mechanism as-' will affect the load center indicator, but when there are empty seats, this knob is used not only to obtain an accurate indication of the location of the load center upon seating of the passengers according to one of the above three plans indicated, but also to indicate the effect upon load center location of reseating the passengers according to an alternate plan at any time.

At the lower center of the panel ill a fuel weight and distribution knob 26 is rotatably mounted,

said knob having an indicating portion 22 movn able with respect to joined weight scales 23 and 2% relating to the front and rear fuel tanks respectively. The front fuel tank is filled first and the rear tank is emptied first in the loading .procedure followed when this instrument is in use, making it possible to thus effect a single entry representing both the weight and distribution of ably mounted a cargo weight distribution knob 85 having an indicating portion 38 movable with respect to a weight distribution scale 37 so that the amount of the cargo which is disposed in the rear cargo space of the craft will be indicated by rotation of the knob 35 to a selected position.

It should be understood that setting movement of knob 35 does not represent the addition of cargo weight to the load previously set by rotation of knob 80, but merely indicate the relative distribution, as between the front and rear cargo spaces, of the cargo weight indicated by the position of the indicating portion" 3| of knob 3|) with respect to scale 32. Therefore the knob 30 must always be set to a weight indication equalling or exceeding that of knob 28.

A rotatably mounted lunch 25 is also provided on the panel III for entering the weight of the oil load, said knob having an indicatingv portion 21 movable with respect to a scale 28 calibrated in gallons.

The empty weight of the airplane, usually with its crew, is entered by rotation ofa shaft provided with a slotted end 88 and may be corrected from time to time. Similarly, the normallocation of the load center may be altered from time the empty weight of the craft the weights of passengers, fuel, oil, and cargo corresponding to the settings of knobs |2, 2t, 26, and 38; the empty weight being first entered by adjustment of slotted shaft 38 until pointer 68 is properlypositioned with respect to its scale 48.

For the purpose of adjusting the pointer 58 to an accurate indication of the empty weight of the craft, the end of shaft 38 at the rear of panel- Ill (Figures 2 and 3) has fixed to it a gear 5! (see also Figure 6) meshing with a rack 52 which is held in engagement with the gear by a guide member 53 fixed to the panel l0, flanges 54 fixed to the gear and overlapping the edge of the rack, and a block 55 secured to the end of the rack. This arrangement is typical of that utilized for the connection of all the racks and lmobs hereinafter described, and therefore no detailed description of such similar connections will be given.v Fixed to the block 55 i a flexible rod 51 pivotally connected at B8 to a link 59 which in turn is pivotally supported at W on a pivot which may be regarded as fixed for the purpose of the present portion of the description. Link 59 is pivotally connected at $2 to a connector 63, the upper end of which is pivotally connected at B4 to a link 65 supported at 6'? on a pivot which may be regarded as fixed for the purpose of the present portion of the description. Link 65 is pivotally connected at 88 to a connector 68, the upper end ofwhich is pivotally connected at II to a link 12 supported at E8 on a pivot which may be regarded as fixed to time, and a second'shaft provided with a I slotted head 39 is therefore provided for resettin the load center location indicator under such circumstances.

The foregoing constitutes the settable devices by means of which the computing mechanism is controlled to give .an indication of the total weight of the craft and its load by moving pointer 40 with respect to scale 4|, and to ive an indication of the location of the center of gravity of the loaded craft by moving pointer 45 with res ect to its scale 46. The computing mechanism can be best understood by regarding it as consistin of first. a weight totalizing portion controlled by the'knobs I2, 20, 25, and 30; second, a moment computing and totalizing portion controlled by the knobs I2,

- I1. 20, 25, 30. and 35; and finally. a portion confor the purpose ofthe present portion of the description. Link 12 is pivotally connected at It to a connector I5, the upper end of which ispivotally connec d at I'I to a weight total-registering element c nsisti of a bellcrank 80 pivotallv mounted at 8| on the panel l0.

For the purpose of visually indicating the weight total registered by displacement of bellcrank 80. a pointer 40 is directly adjusted by movement of the bellcrank 80 on its pivot 8|. For this purpose bellcrank 88 is pivotally connected at 82 to a fiexible rod 83, the lower end of which is pivotally connected at 81 to an arm 85 secured to a shaft 86 upon which the pointer 40 is likewise secured. Spring 81, tensioned between the arm 85 and a stud 88 in panel It, tends to move pointer 40 toward the lower end of its scale ll, taking up in one direction any back lash or lost motion in the train of connections between the pointer and the settable devices connected to it.

For the purpose of adjusting the pointer 40 a to indicate the weight of the fuel load in addition to the empty weight of the craft and the other loads, the knob 2|) is fixed to a shaft 90 (Figures 2 and 3) journaled in the panel l0 and provided with a gear 8| fixed to the end thereof at the rear of panel l0. Held in mesh with gear 8| by an arrangement corresponding to that previously described, is a rack 92 to which is fixed a flexible rod 83 pivotally connected at to the previously described link 89.

This arrangement is such that upon clockwise movement of knob 20 (Figure l) rack Q2 and rod 82 are moved downwardly, rocking link 59 about pivot 58 as a fixed pivot, link 65 about pivot 51 as a fixed pivot, link 12 about pivot I8 as a fixed pivot, and bellcrank .80 about its pivot 8|, to produce clockwise movement of pointer as the same is viewed in Figure 1. The lengths of the its scale 4| efi'ective lever arms in this train are'fixed so that the advance of pointer 40 with respect to its scale 4| will be proportionate to the weight of the volume of fuel indicated by the position of indicator 22 with respect to scales 23 and 24 in all positions of knob 20.

For the purpose of adjusting the pointer 40 to indicate the weight of the cargo load in addition to the empty weight of the craft and the other loads, the knob 30 is fixed to a shaft 95 (Figures 2 and 3) journaled in the panel I0, and provided with a gear 06 fixed to the end thereof at the rear of the panel I0. Held in mesh with gear 96 by an arrangement corresponding to that previously described is a rack. to which is fixed a flexible rod 08 pivotally previously described link 85.

This arrangement is such that upon clockwise movement of knob 30 (Figure 1), rack 91 and rod 98 are moved downwardly rocking link 05 about 64 as a fixed pivot, link 12 about pivot I3 as a fixed pivot, and bellcrank 80 about its pivot 8|, to produce clockwise movementof pointer 40 as the same is viewed in Figure 1. The lengths of the effective lever arms in this train are .fixed so that the advance of pointer 40 with respect to will be proportionateto the weight of the cargo indicated by the position of indicator 3| with respect to scale 32 in all'positions of knob 30.

For the purpose of adjusting pointer 40 to indicate the weight or the passenger load in addition to the empty weight of the craft and the other loads, the knob I2 is fixed to a shaft IOI (Figures 2 and 3) journaled in the panel I and provided with a gear I02 fixed to the end thereof at therear of the panel I0. Held in mesh with gear I02 by an arrangement corresponding to that previously described, is a rack I03 to which is fixed a flexible rod I 04 pivotally connected at I05 to a link I06 supported at I07 on a pivot which may be regarded as fixed for the purpose of the present portion of the description.

connected at 51 t the 4 ment under such circumstances. All of the lever about I05 as a fixed pivot, link 12 about II as a fixed pivot, and bellcrank 80 about its pivot 0|, to produce clockwise movement of pointer as the same is viewed in Figure 1. The lengths of the efiectlve lever arms in this train are fixed so that the advance of pointer In with respect to its scale 4| will be proportionate to the weight of the volume of oil indicated by the position of indicator 21 with respect to scale 28 in all positions of knob 25.

Because the several classifications of loads designed to be carried are not ordinarly of the same magnitude, the calibration of the scales associated with the various knobs will not usually be on the same scale. The movement imparted to the pointer 40 by each knob is controlled by the lever systems connecting the knobs with the pointer, however, so that the advance of the pointer with respect to its scale corresponds with the advance of each knob with respect to its scale, and in instruments designed for various types of aircraft the calibrations and lever systems may be altered in accordance with the capacities and weight locations involved.

It will be observed that although for the purposes of explanation the various levers have been described as rocking about designated points as fixed pivots, this is true only when the knobs are set separately, the frictional resistance of the other knob assemblies preventing their displacesystems are so constructed, as shown in the drawings, as to permit any number of the knobs to be set concurrently, and undersuch circumstances the pointer will be advanced proportionately to the sum of the individual knob movements.

The various we craft being totalized and added to the empty Link I06 is pivotally connected at I08 to a connector I09, the upper end of which is pivotally connected at 10 to the previously described link i2.

This arrangement is such that upon clockwise movement of knob I2 (Figure 1), rack I 03 and rod I04 are moved downwardly rocking link I06 about I01 as a fixed pivot, link 12 about II as a fixed pivot, and bellcrank 80 about its pivot 8i, to produce clockwise movement of pointer 40 as the same is viewed in Figure l. The lengths of the effective lever arms in this train are fixed so that the advance of pointer 40 with respect to its scale II will be proportionate to the total of the assumed average weights of the number of passengers indicated by the position of indicator I3 with respect to scale I! in all positions of knob I2.

For the purpose 'of adjusting pointer 40 to indicate the weight of the oil load in addition to the empty weight of the craft and the other loads, the knob v25 is fixed to a shaft III (Figures 2 and 3) journaled in the panel I0 and provided with a gear II2 fixed to the end thereof at the rear of the panel I0. Held in mesh with gear II2 by an arrangementcorresponding to that previously described is a rack II: to which is fixed a flexible rod Ill I01 to the previously described link I06.

This arrangement is suchthat upon clockwise movement of knob 25 (Figure l) rack H3 and rod H4 are moved downwardlyrocking link I00 signed, the front fuel, tanks pivotally connected at mechanism actuated by movement 01' the weight of the craft by the mechanism thus far described, the portion of the instrument which simultaneously computes and algebraically totalizes the separate moments exerted by these weights may be the next logical subject of consideration.

. This moment computing and totalizing portion tiplying a movementproportionate to the magnitude of each given weight by a constant pro= portionate to the distance at which said weight is-located from the normal load center oi the craft. The separately computed moments are concurrently totalized by difi'erential displacement of a moment total registering element, but no direct visual indication of the magnitude of the totalized moments is provided for in the present instrument because it is significant only as a factor in the computation of the lineal displacement of the load center as hereinafter described.

The moment total registering element consists, in the illustrated embodiment of the invention, of a lever I25, most clearly'shown in Figurese, 5,. and 6, which lever is pivotally mounted at I28 on the panel Ill, and pivotally connected at I 21 to an actuating lever I20.

Inthe particular craft for which the instrument illustrated and described herein was de-' are wing tanks, and their location with respect to the longitudinal axis of the craft is substantially coincident with that of the normal load center thereof.

serves to compute the separate moments'by mulknob 20 within the limits of scale 23, relating to the front .fuel tanks, should not, therefore. displace the momenttotal registering lever I 25 at all, and it will be noted, on reference to Figures 2 and 3,

ights making 'up the load of the.

The

' to permit rotational brought into contact as a fixed pivot. Pivotally connected at I40 is a link I, the upper end of which is 4 that the rack 92 actuated by this knob 20 has no direct connection with said lever I25 and that therefore no displacement of said leverwill attend the adjustment of knob 20 within the limits 'ofscale 23.

The rear fuel tanks, however, are located rearward of the normal load center of the craft, and

a lost-motion connection is therefore provided between the rack 92 and mechanism for displacement the moment total registering lever use o that adjustment of knob 20 within the I32 against an eccentric stud I33 secured to the panel I by a screw I which may be loosened stud for the purpose of eflecting adjustment of the limit position of lever I30; Stud I38 is so located with respect to the lower end of rack 92, that movement of knob within the limits of scale 23, will not bring the lower end of rack 92 into contact with lever I30, but upon movement of mob 20 within the limits of scale 24, rack 92 is with a stud I 85 fixed tolever I00 so that all further clockwise movement of knob 20- eflects clockwise rocking oflever I30 about its pivot I3I.

Such movement of lever I30 is transmitted to the moment total registering element by-means comprising a rod I31 pivotally connected at its lower end, at I38, to the left end of lever I80; and

pivotally connected at its upper end, at I39, toa lever I40, whereby upon lever I50, lever I50 is rocked clockwise about I42 to lever I00 pivotally connected at IN to a lever I41, whereby lever I41 i rocked clockwise about I48 as a fixed pivot. Pivotally connected to lever M1 at I50 is a link I5I, the upper end of which is pivotally connected at I52 to the actuating lever I28 hereinbefore described, which in this operation i rocked clockwise about I53 (see Figure 4) as a fixed pivot, and through its pivotal connection I21 with the moment total registering lever I rocks the latter clockwise about its pivot I25. The lengths of the effective arms of the levers d scribed are so proportioned that the difierential displacement of lever I25 so brought about is proportional to the moment exerted by the rear fuel tank load about the normal load center of the craft.

For the pm'pose of effecting differential dis placement of the moment total registering lever I25, in accordance with the moment exerted by the cargo load in the front cargo compartment. the rack 51' actuated by the knob is connected to lever I25 by means comprising a rod I55 connected to said rack and pivotally connected at its upper end, at I58, to a lever I51, whereby upon clockwise movement of knob lever I51 is rocked clockwise about I58 as a fixed pivot. P'votally connected at IBQ -to lever I51 is a link IN, the

upper end of which is pivotally connected at I52 to a lever I53 which in this operation is rocked counterclockwise about I08 as a fixed pivot.

Pivotally connected to lever I65 atv I58 is a link I51 the upper end of which is pivotally connected at I53 (see also Figure 4) to the actuating lever I28 which in this operation is rocked counterclockwise about I52 as a fixed pivot, and through adjustment of the eccentric clockwise movement of its pivotal connection I21 with the moment total registering lever I25 rocks the latter counterclockwise about its pivot I25. The lengths of the placement of lever I25 in this operation is opposite to that described in connection with the rear fuel load.

In the craft for which the present instrument was designed, two cargo spaces are provided; one forward of the normal load center of the craft, and the other rearward thereof. Computation of the load center location under various load distributions is facilitated by arranging-the computing mechanism relating to these cargo spaces so that the entire cargo load is registered by rotation of one of two knobs; in this case, the knob 30 just referred to. A has been described, this knob actuates both the weight totalizing and moment computing and totalizing mechanisms. The associated knob 35 (Figure 1) has no connection whatever with the weight totalizing mech anism, but actuates the moment computing and totalizing mechanism through leverages which are so proportioned that the differential displacement of the moment total registering lever I25 effected by adjustment thereof is proportional not only to the moment exerted by the rear cargo compartment load about the normal load center of the craft, but is also proportional to the decreased moment exerted by the front cargo compartment load previously set into the instrument by knob 30 minus the portionv of that load indicated to have been moved to the rear cargo compartment by the setting of knob 35v The connection between knob 35 and the moment total registering lever I25, for this purpose. comprises a shaft I10 extending through panel III, knob 35 being secured to one end of said shaft and a pinion I1I being secured to the other end (III thereof and enmeshed with a rack I12, the arrangement corresponding in general to that described in connection with the other knobs. However, it will be noted that, as shown in Figures 2 and 3, the rack m is so located with respect to the pinion I1I that clockwise movement of the knob 35 will raise instead of lowering the rack. A

rod I13 secured to rack I12 is pivotally connected partment load indicated by the position of knob 35 with respect to scale 31, the excess movement being proportionate to the decrease of the moment in the opposite direction effected by removal of an equal load from the front cargo compartment.

For the purpose of effecting difierential displacement of the moment total registering lever I25 in accordance with the moment exerted by the passenger load, an additional rack I15 is provided, which meshes with the gear I02 on the side thereoi. opposite rack I82 so that when the knob I2 is set, rack III is displaced an amount equal to the displacement of rack I88, but in the opposite direction. Rack H5 is connected to lever I by means comprising a rod I18 connected to said rack and pivotally connected at its upper end, at I82, to the previously described lever I48, whereby upon clockwise movement of knob I2, lever I48 is rocked counterclockwise about I38 as a fixed pivot. Through the previously described connections comprising link I 48, lever I41, link I5I, actuating lever I28 and its pivotal connection I2 with the moment totaling registering lever I25, the latter is diflerentially adjusted in a clockwise direction.

Since all of the passenger weights delineated upon Scales I4 and I5 cannot be placed at the same distance from the normal load center of the craft, means are provided for varying the rate at which lever I25 is displaced during the progressive advance of knob I2 with respect to those scales.

In the particular craft for which the instrument herein illustrated and described was designed, the location of the front passenger Seats is forward of the location of the normal load center of the craft, one row of seats is, substantially coincident with the normal location of the load center, and the majority of the seats are rearward of the normal load center.

Therefore, when passengers are loaded first in the front seats and then progressively rearward ly, it is necessary for the movement transmitted to lever I25 ,by knob I2 to be initially decelerated in one direction, then substantially arrested during a part of the movement of knob I2, and finally to be gradually accelerated in the opposite direction.

When passengers are loaded first in the rear seats and then gradually forward, this situation I is reversed, and during the same movement of knob I2, lever I25 must be first given a, gradually decelerated movement in a direction opposite to that of its initial movement in the first case, then it must be substantially arrested during a part of the movementofknob I2 and finally it must be gradually accelerated in the opposite direction to that in which it was first moved.

When passengers are loaded first in the center seats and then equally in each direction toward the and seats the rate at which lever I25 is moved by knob I2 should be substantially uniform throughout the movement of the latter.

This progressive changing of the rate of movement of lever I25 by knob I2 is accomplished by means comprising a'rod I88 (Figure 3) connected length between pivots, and the to the rack I88and pivotally connected at its upper-end at I8I to a link I82 pivotally mounted on the panel III at I88. Link I82 is pivotally connected at I88 to one end of a second link I 85, forming a toggle linkage, the other end oi which is pivotally connected at I88 to one link I810! a scissors linkage pivotally mounted on the panel vIlat I88. linkage include a second nected at I8I to the upper end of link I8'I (see Figure 7), and a third link I82 pivotally connected to the link I88 at I88 and to a lever I85 at I84. Lever I85 is pivotally mounted on the panel I8 at I8'I,and its opposite end is pivotally connected at I88 to a rod I88, the upper end of The other elements of this scissors link I88 pivotally conwhich is pivotally connected to the lever I41 I which is movable, in the same manner previously described in connection with the other racks, by the knob II disposed on the face of panel I8.

When the knob I1 is set so that its indicator I8 points to Center on scale I8, the pivot I93 connecting links I88 and I82 of the scissors linkage is positioned by rack 282 and rod 288 so that the axis thereof is coaxial with the axis of the pivot I88. When this mechanism is so set, movement oi. the toggle linkage I82, I by knob I2 via rack I83 and rod I88 will not cause any movement of the lever I85, because all of the links of the scissors linkage I8I, I88, I82 are of equal movement of the toggle linkage I82, I85 from the position in which it is shown in Figure 3 to the position in which it is shown in Figure 2, will merely oscillate scissors links I81 and I88 around the,coaxia1 pivots I88 and I 83 as a center, without imparting any movement to scissors link I82 and lever I85 connected thereto. Under-such circumstances the movement of the moment totalizing lever by knob I2 will be uniform at all times during the adjustment oi. the latter.

When the knob I1 is set so that its indicator I8 points to Front to Rear on scale I8, the pivot I83 is displaced-from coaxiality with the pivot I88 as shown in Figure 3. Under such circumstances downward movement of rack I88 from the position in which it is shown in Figure 3 will, as it straightens the toggle linkage I82, I88, rock the link I81 clockwise about its pivot I88 and, through link I88, will move. pivot I88 downward, flexing rod 288 slightly. Downward movement of pivot I88, through link I82 and pivot I84, rocks lever I85 clockwise about pivot I81, and, through rod I88 lowers pivot I88.

It will be recalledthat the transmission of to lever I25 is by way of rack I15, rocl I18,1ever I88, link I, and lever I l'I which rock s. clockwise about pivot I88 as rack I15 is raised. The concurrent lowering of pivot I48 as above described, therefore decreases the movement transmitted from lever Ml to link I56 and actuating lever I23. During the first part of the movement of knob I2 the rate at which pivot I88 is thus lowered is sufllcient to more transmitted to lever I58 is first lowered,

,2, pivot I 48 is raised at an accelerating rate.

This raising of pivot I48 causes pivot I58 to be raised not only by the movement transmitted from knob I2 by way of link I, but an additional amount proportionate to the amount by which pivot I88 is raised, and since the rate at which pivot I88 rises increases progressively during movement of the toggle linkage from straight position to the position in which it is shown in Figure. 2, it will be seen that the rate at which lever I25 is moved progressively increases.

.The arrangement described is therefore such that when knob I1 is set at "Front to Rear, the movement of knob I2 along its scale effects a reversal of the direction, followed by a gradually accelerated movement of the moment totalizing lever I25; when knob I'I isset at Center the movement of knob I2 along its scale effects a uniform proportionate movement of lever I25; and when knob I1 is set at Rear to Front exactly the reverse of the movement when it is set at Front to Rear" takes place; i. e., movement of knob I2 effects a gradually decelerated movement of lever I25 followed by a reversal of the direction of movement. It will also be observed that a resetting of knob I1 from anyof its indications to another will, at any time, effect the appropriate repositioning of lever I25 by raising or lowering pivot I48.

The lengths of the effective arms of all of the levers described in connection with this operation, are proportioned so. that the differential displacement of lever I25 is proportional to the moments exerted by the passenger loads about the normal load centerof the craft.

For the purpose of effecting differential displacement of the moment total registering lever I25 in accordance with the moment exerted by the oil load, rack H3 is pivotally connected at 204 (Figure 3) by a rod 205 to a lever 206, rookable about pivot 201. Lever 206 has pivotally connected thereto, at 208,'a rod 209, the upper end of which is'pivotally connected to lever I51 at I58. This arrangement is such that adjustment of the oil knob 25 eflects a proportionate differential adjustment of lever I25 through connections comprising rod 205, lever 20B, rod 209, lever I51, link IIiI, lever I63, link [61, actuating lever I28, and pivotal connection I21.

The lengths of the effective arms of all of these levers are proportioned so that the differential displacement of lever I25 is proportional to the moment exerted by the oil load about the normal load center of the craft.

A normalizing adjustment of the moment total registering lever I25 necessary, for instance, when changes are made in the fixed equipment load, may be effected by adjustment of shaft 39 provided with a slotted head, as shown in Figure 1. This shaft is connected, by a pinion corresponding to that described in connection with the various setting knobs, to a rack -2I I, which in turn is connected to a rod 2I2, the upper end of which is pivotally connected at 201 to lever 206 and moves lever I25 throughth'econnections above described in connection with the description of the oil knob.

The bell crank 80, which is directly connected to the pointer 20 and therefore constitutes a weight total registering element, having been set to a position representative of the total of the empty weight of the craft and the various weights making up its load, and the moment total registering element I25 having been set to a position representative of the algebraic total of the in dividual moments exerted by the various loads about the normal load center of the craft, all as above described, the mechanism for dividing the algebraic sum of these moments by the total of the weight in order to obtain an indication'of the lineal displacement of the load center will be described.

The mechanism for performing this computation and indicating the quotient in lineal terms isshown in detail in Figures 5 and 6. Indicator 45 which is movable over scale 42 is fixedly mounted on an arbor 225 to which is also fixed an arm 223 pivotally connected at 221 to an actuating rod 228. Spring 230 tensioned, between the arm 220 and a stud on the panel Ill urges the assembly in one direction eliminating any efiect from back lash in the various connections.

The opposite end of rod 228 is pivotally connected at 23I to one element 232 of a scissors linkage comprising links 232, 233, and 232 of equal length between their pivot centers; link 232 being pivotally mounted on panel III at 230 and pivotally connected at 231 to the link 233 which is, in turn, pivotally connected at 238 to the link 234. I

This scissors linkage is controlled and actuated by the weight total registering bellcrank 00 and the moment total registering lever I jointly.

Bellcrank 80 is connected thereto by alink 240 pivotally connected to the bellcrank 80 at 24I, and to the scissors linkage at the pivot 238 which also connects the links 233 and 234. lever I25 is connected thereto by means comprising a rod 242, the upper end of which is pivotally connected to lever I25 at 243 and the lower end of which is pivotally connected at 24:4 to a lever 245 pivotally mounted on panel I0 at 246, which lever is, in turn, pivotally connected to link 234 of the scissors linkage at 241.

This arrangement is such that any variation in the moment total registration as represented by the positions of lever I25, in either direction, will rock lever 245 about its pivot 246, and, through links 234 and 233, will rock link 233 and the indicator 45 directly connected thereto. The extent t which indicator 45 will be displaced by a given rocking of lever I25 in this manner is dependent upon the positioning, by the weight total registering bellcrank-80, of the pivotal connection 238 between links 233 and 234. As the weight registration decreases, pivot 238 is moved toward coaxility with pivot 236 (they would be coaxial at a zero weight registration) and a given movement of lever I25 produces a greater movement of pointer 45 as this distance between pivots 230 and 238 is reduced.

Similarly, if the moment registration remains constant at a value other than zero and the weight total is changed, pointer 35 is repositioned accordingly, the parts being so proportioned that each successive doubling of the weight under .such circumstances would indicate only half as much lineal displacement of the load center.

The instrument herein described is a preferred embodiment of my invention and clearly fulfills the objects stated hereirrabove, but it will be apparent that many modifications are possible and desirable in designing specific instruments for various types of craft. The invention therefore isnot to be considered as restricted to the form disclosed except in so far as is necessitated by the prior art and by the spirit of the appended claims.

I claim:

1. In a computer, first and second settable value entering devices, a member differentially adjustable to form a, mechanical representation of a computed value, a first means controlled by said first device for effecting differential adjustment of said member, a second means for efiecting differential adjustment of said member, means controlled by said first device and comprising movement, reversing mechanism for actuating an element of said second means in opposite directions successively upon settingmovement of said first device in a single direction, and means controlled by said second device for actuating an element of said second means.

2. In a computer, first and second settable value entering devices, a, lever differentially adjustable to form a mechanical representation of a computed value, connections extending from adjacent one end or said lever to said first device for effecting diflerential adjustment oi. said lever upon setting movement of said device, means having an operating connection with said lever adjacent the opposite end thereof for effecting differential adjustment of said lever, mechanism comprising a toggle linkage having an operating connection with an element of said means, and an operating connection with said first device for actuating an element of said means in opposite directions upon setting movement of said first device in a single direction, and connections between said second device and an element of said means for actuating the latter upon setting movement of said second device.

3. In a computer, registering means including a value entering device settable through a predetermined range, computing means including an element differentially adjustable to form a mechanical representation of a computed value,

vmeans controlled by said value entering device i during setting thereof through a portion only of said predetermined range for actuating said computing means, means effective during setting of said value entering device through a portion of said predetermined range for superseding the control of said computing means by said actuating means, and result registering mechanism controlled jointly by said registering means and said computing means.

4. In a computer, registering means including a value entering device settable through a predetermined range, reversibly operable computing means including an element differentially adjustable to form a mechanical representation of Ma s. computed value, spring means f r op at said computing means in one direction, stop means for limiting the extent of operation of said computing means by said spring means, means engageable by a portion of said registering means only after movement of said value entering device through a portion of said predetedmined range for operating said computing means in the opposite direction, and result registering mechanism controlled jointly by said registering means and said computing means.

5. In a computer, a plurality of means for registering separate values occurring in a mathematical equation, means comprising an adjustable value entering device common to said plurality or registering means for simultaneously entering values in said plurality of registering means, and means responsive to one portion of said value entering means upon the entry of a value in one of said registering means thereby tor actuating another portion or said value entering means in opposite directions upon movement of said portion of said valve entering means in a single direction to vary the value entered in another 01 said registering means by said last mentioned portion or said value entering means in corresponding opposite directions.

8. In a, computer, a lurality or means for re istering separate values occurring in a" mathematical equation, means comprising an adjustable value entering device commonto said plurality of registering means tor simultaneously entering values in said plurality of registering means, and means responsive to one portion or said value entering means upon the entry of a value in one of said registering means thereby for actuating another portion of said value entering means in opposite directions upon movement oi. said portion of said value entering means in a single direction to vary the value entered in another or said registering means by said last mentionedportion of said value entering means in corresponding opposite directions; said actuating means including 1a, portion selectively ad justable to alter the magnitude of the variation in value entered in said other registering means by a given adjusting movement of said value entering device, and means comprising a second adjustable device for selectively adjusting the selectively adjustable portion of said actuating means.

7. In a computer, a plurality of means for registering separate values occurring in a mathetering values in said plurality of registering I means, and means responsive to one portion of said value entering means upon the entry of a value in one of said registering means thereby for actuating another portion of said value entering means in opposite directions upon movement of said portion of said value entering means in a single direction to vary the value entered in another of said registering means by said last mentioned portion of said value entering means in corresponding opposite directions; said actuating means including a p rtion selectively adjustable to reverse the sign character of the variation in value entered in said other registering means by a given adjusting movement of said value entering device, and means comprising a second adjustable device for selectively adjusting the selectively adjustable portion of said actuating means.

8. In a computer, a plurality of means for registering separate values occurring in a mathematical equation, means comprising an adjustable value entering device common to said plurality of registering means for simultaneously entering values in said plurality of registering means, and means responsive to one portion of said value entering means upon the entry of a value in one of said registering means thereby for actuating another portion of said value entering means in opposite directions upon movement of said portion of said value entering means in a single direction to varythe value entered in another of said registering means by said last mentioned portion of said value entering means in corresponding opposite directions; said actuating means including a portion selectively adjustable between indicated limit positions to reverse the sign character of the variation in value entered in said other registering means by a given adjusting movement of said value entering device, and to an indicated intermediate position to render said valve entering device ineifective to vary the value entered in said another of said registering means, and means comprising a second adjustable device for selectively adjusting the I selectively adjustable portion of said actuating 

